/*
 * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
 *
 * You are hereby granted a non-exclusive, worldwide, royalty-free license to use,
 * copy, modify, and distribute this software in source code or binary form for use
 * in connection with the web services and APIs provided by Facebook.
 *
 * As with any software that integrates with the Facebook platform, your use of
 * this software is subject to the Facebook Developer Principles and Policies
 * [http://developers.facebook.com/policy/]. This copyright notice shall be
 * included in all copies or substantial portions of the software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package com.facebook.bolts

import java.io.Closeable

/**
 * Represents a callback delegate that has been registered with a [CancellationToken].
 *
 * @see CancellationToken.register
 */
class CancellationTokenRegistration
internal constructor(tokenSource: CancellationTokenSource, private var action: Runnable?) :
    Closeable {
  private var closed = false
  private var tokenSource: CancellationTokenSource? = tokenSource

  /** Unregisters the callback runnable from the cancellation token. */
  override fun close() {
    synchronized(this) {
      if (closed) {
        return
      }
      closed = true
      tokenSource?.unregister(this)
      tokenSource = null
      action = null
    }
  }

  internal fun runAction() {
    synchronized(this) {
      throwIfClosed()
      action?.run()
      close()
    }
  }

  private fun throwIfClosed() {
    check(!closed) { "Object already closed" }
  }
}
